The Christian Church started in the Middle East. As it spread across the known world, each region evolved its own expression of the Apostolic Tradition. There are two heritages that dominate Christianity today: the Eastern and the Western. Western Christianity has influenced the societies of western and northern Europe. The rest of Europe, Asia and Africa was influenced by Eastern Christianity.

For the first few centuries of Christianity there were five great Apostolic Churches located in the most important, powerful, religiously significant cities of the ancient world — Jerusalem, Rome, Constantinople, Antioch, and Alexandria.

Each of these great Churches has Apostolic origins: Saint James the Brother of the Lord was the first bishop of Jerusalem; Saints Peter and Paul founded the Church in Antioch; Saint Peter later presided in Rome; Saint Andrew, his brother, presided in Constantinople; and, Saint Mark the Evangelist founded the church in Alexandria.

It is from the Roman church that most European and American churches draw their traditions and rituals. Some Eastern Churches drew their inspiration from Constantinople. These Eastern Christians are often called "Greek" because their origins are in the Greek-speaking Roman empire of the eastern Mediterranean. They are often called Byzantine as well.

The Eastern Christian churches today belong to many groups and families, some of which are Antiochian, Armenian, Coptic, Greek, Melkite, Russian, Ruthenian, Syriac, and Ukrainian. Some are Catholic while others are Orthodox.